Tilting mechanism for a lifting implement



Feb. 11, 1969 A. M. VIK 3,426,929

TILTING MECHANISM FOR A LIFTING IMPLEMENT Filed Dec. 5, 1966 I H" PM 216 "mum...

FIE 5 INVENTOR.

BY wk wm Feb. 11, 1969 A. M. VIK 3, 2 2

TILTING MECHANI SM FOR A LIFTING IMPLEMENT Filed Dec. 5, 1966 Sheet 2 ms INVENTOR. 4484M M V/z TILTING MECHANISM FOR A LIFTING IMPLEMENT Sheet v3 bf a INVENTOR.

BY W

ATI'OEIVEV United States Patent lll Claims ABSTRACT OF THE DISCLOSURE A tilting mechanism for a lifting assembly such as a clamp mechanism or scoop for a front end loader that is mounted on the front or free end of the boom. A connecting link is pivoted to the lifting assembly. This link extends back from the pivot point toward the boom and is connected at its free end to a hydraulic actuator mounted upon the top of the boom. A fixed stop is welded to the lifting assembly for limiting the movement of the end of the connecting link about the pivot in one direction so that the lifting assembly will be supported from the link during the first extension of the hydraulic actuator and continued extension of the hydraulic actuator will cause the load to be shifted partially to the fixed stop. A gravitationally actuated movable stop swings into position against the opposite side of the link from the fixed stop when the lifting assembly is in its lowest position so that continued extension of the hydraulic actuator will continue to swing the lifting assembly beyond its lowest position and through a total arc of as much as 230 or more.

The present invention relates to lifting and loading equipment of the type used in materials handling and more particularly to a mechanism for tilting an assembly which is mounted for articulation at the end of a supporting boom.

Among the most common loading or lifting implements in current use are those known as front-end loaders, back hoes, scoop excavators, power-operated lifting clamps and the like. In each of these implements, an arm member sometimes referred to as a boom is mounted so as to extend forwardly from a pivotal support at the rear of the vehicle. A suitable actuator such as a hydraulic cylinder is connected to the boom for elevating the forward end of the boom. A scoop, clamp or other lifting assembly is secured at the forward end of the boom for articulation about a horizontal axis. One or more cylinders are ordinarily connected between the boom and the lifting assembly for tilting the lifting assembly about the axis of articulation. While the lifting assembly in these prior devices can theoretically approach a total tilting arc of about 180, the practical arc through which the lifting assembly is able to move is about 90-l00 since very little force can be applied at each end of the stroke when the cylinder is in alignment with the pivot axis upon which the lifting assembly turns. It is consequently impossible to extend or lower the point at which the hydraulic cylinder is connected to the lifting assembly below the boom axis (an over-center position). This is particularly objectionable in the case of a power-operated lifting clamp because in order to reliably unload material being carried in a drum or other receptacle, it is necessary to pivot the drum substantially beyond 90 and frequently as much as 180 3,426,929 Patented Feb. 11, 1969 from its starting position to successfully prevent material from being inadvertently trapped inside. The boom is usually inclined at a steep angle (about 45) when in its lowered position with the front end to which the load is connected in a lower position than the rearward end. When the boom is raised to a horizontal position, the fiber drum or other receptacle will be inclined rearwardly, in other words, towards the operator of the vehicle at an angle of about 45. Accordingly, if material is to be dumped from the drum, it must be pivoted or tilted forwardly through an arc of about in order to achieve a horizontal position. In practical operation, it must be tilted somewhat beyond that position for material to be removed. Furthermore, it is often difficult to design such equipment so that an are as large as can be negotiated without interference between the various parts such as connecting rods, pivots and lifting assembly.

In view of the shortcomings of the prior art, it is one object of the present invention to provide an improved tilting mechanism for a loading implement wherein the extension of an actuator or cylinder is capable of tilting the lifting assembly through an arc of about 180.

Another object of the invention is the provision of an improved tilting mechanism of the type described in which the connection between the cylinder and the lifting assembly is continually raised relative to the point of articulation between the boom and the lifting assembly as the lifting assembly is tilted forwardly.

Still another object of the invention is the provision of an improved tilting mechanism of the type described including a connecting element secured between the lifting assembly and the actuator and a movable locking member for retaining the connecting element in a selected position.

Another object of the invention is the provision of a tilting mechanism of the type described which is adapted for attachment to a variety of implements employed for lifting and loading materials.

A more specific object is the provision of an improved tilting mechanism for a lifting assembly articulated upon the forward end of a boom of a bucket loader, scoop loader, front-end loader, power-operated clamp or the like.

A further object of the invention is the provision of an improved tilting mechanism of the type described in which the movement of the free end of the cylinder connecting rod through an arc of about 130 relative to the supporting boom is adapted to turn the lifting assembly through an arc of about 180 relative to the supporting boom.

Still another object of the present invention is the provision of an improved tilting mechanism of the type described in which the cylinder as it is extended acts first as a tension element for supporting the lifting assembly and during the last portion of its travel as a pressure exerting member for elevating the lifting assembly toward the operator from its lowermost position.

A still further object of the invention is the provision of an improved tilting mechanism for a lifting implement including an element connected between the free end of the cylinder and the lifting assembly and an entirely selfcontained locking mechanism for securing the connecting element in a rigid position relative to the lifting assembly when the lifting assembly has been tilted to a predetermined position.

These and other more detailed and specific objects will become apparent in view of the following specification and claims and by reference to the drawings wherein:

44 of FIGURE 3 on a still larger scale with the lifting I assembly in a horizontal position.

FIGURE 5 is a view similar to FIGURE 4 showing the lifting assembly as it appears when lowered through an arc of approximately 45 from the position shown in FIGURE 4.

FIGURE 6 is another view similar to FIGURES 4 and 5 showing the lifting assembly as it appears when tilted through an arc of about 110 from the position of FIG- URE 5 relative to the axis of the boom.

FIGURE 7 is a view similar to FIGURE 6 with the lifting assembly tilted an additional To the accomplishment of the foregoing and related ends, the invention then comprises the features hereinafter set forth and particularly pointed out in the claims, the following description being indicative of but a few of the ways the invention can be employed.

In brief terms, the invention provides a connecting element or link couple-d at its ends between a lifting assembly mounted on the end of the boom of a materials handling implement and an actuator, e.g., a hydraulic cylinder,

secured to the boom for tilting the lifting assembly. The connecting element, preferably formed from a rigid piece of material, is secured by a first pivot at one end of the lifting assembly and by a second pivot at the other end to the actuator rod or connecting rod of the hydraulic cylinder. A fixed stop is operatively associated between the connecting element and the lifting assembly for limiting the movement of the connecting element about its pivot on the lifting assembly in at least one direction.

The stop can conveniently consist of a metal plate welded J to the lifting assembly and positioned to limit the movement of the free end of the link toward the cylinder.

In a preferred from of the invention, a provision is made for limiting the motion of the free end of the connecting element relative to the lifting assembly in the opposite direction (away from the cylinder) when the cylinder has moved the lifting assembly to a downwardly depending position (its lowest point).

A preferred form of the invention will now be described in more detail by reference to the figures. As shown in FIGURE 1, a tilting mechanism is provided at the end of a rigid boom assembly composed of two parallel laterally spaced forwardly extending sections designated 210a and 21% on the left-hand side of the vehicle and sections 212a and 21212 on the right hand side of the vehicle. The boom sections are pivotally secured at their rearward ends by means of a laterally disposed horizontally extending pivot 214 to a vehicle 216 or other loading implement. A suitable actuator such as a hydraulic cylinder 218 is secured between the vehicle and the boom sections for raising and lowering them about the pivot 214.

At the top of each of the boom sections 210a and 212a are secured actuators exemplified by cylinders 220 and 222. The cylinders include the usual actuator or connecting rods designated 220a and 222a respectively. The free end of the connecting rods 220a and 222a are secured by pivots 224 and 226 to connecting elements such as a pair of links 228a and 228k on the left-hand side of the implement and a pair of similar links 230a and 23011 on the right-hand side of the implement and it is these links which connect the actuators 220 and 222 to the lifting assembly 232. Each link has an extension designated E on the lower side of the pivot 262. The lifting assembly 232 in this instance comprises a clamp mechanism of any known construction, for example that de- 4 scribed in my co-pending patent application, Ser. No. 563,165, filed July 6, 1966 and now Patent No. 3,393,855. The clamp mechanism 232 includes jaws 236 and 238 which engage a steel drum 240.

As seen in FIGURE 2, the invention can be applied for a variety of other applications, in this case for tilting a scoop 241 of well-known construction including side walls 243, a bottom wall 245 and teeth 247 at its forward edge for the purpose of loosening soil or gravel.

Each side of the lifting assembly 232 is composed of a pair of parallel longitudinally extending laterally spaced plates. The pair of plates on the left are designated 240 and 242, those on the right are designated 244 and 246. The plates are secured to each other by suitable spacers 248 and 250 and are fastened to the center portion of the lifting assembly 232 by means of brackets 252, 254 and 256. Other points of attachment can be employed as needed. The end of the boom 21011 is pivotally secured to the plates 240 and 242 by means of a transversely extending pivot 260. The boom section 212b at the right of the apparatus is secured between plates 244 and 246 by means of a pivot 261 (FIGURE 3) positioned in alignment with pivot 260. In this manner, the lifting assembly 232 is free to articulate about a horizontally disposed transverse axis extending between the pivots 260 and 261.

The link members 228a and 22812 as well as the link members 239a and 23Gb are pivotally secured to the respective plates by means of transversely extending horizontally disposed and aligned pivot pins 262 and 263. Spaced a short distance from the pin 262 is a fixed stop 264 on the opposite side of pin 262 from the boom pivot 260. As clearly seen in FIGURE 3, the stop 264 is composed of two plates each secured rigidly as by welding to one of the plates 240 and 242. The stops on the righthand side of the apparatus have been designated 266 and are similarly positioned. While the stops 264 have been illustrated as flat plates, any suitable rigid member such as a rod or tube can be employed.

Mounted for movement about a horizontally extending transverse pivot 268 are provided two identical independently movable stops 270a and 2701). Stop 270a is positioned in alignment with the link 228a and the stop 27012 is positioned in alignment with the link 22%.

Similar stops 271a and 27111 are provided on the righthand side of the apparatus in alignment with the links 230a and 230i). Their operation is exactly the same as that of the stops 270a and 27%. Weights 272 are preferably provided at the lower end of each movable stop. The movable stops also include forwardly projecting extensions 274 having a forward edge 276 adapted to contact the rearward edge of the links at certain times as will be described more fully below. The position of the movable stops is determined entirely by gravity. A rest such as a piece of bar stock 271 is preferably provided on the lower portion of the lifting assembly to limit the counterclockwise movement of the movable stops. Each of the movable stops is independently movable thereby assuring proper operation of the apparatus even if one of the movable stops becomes stuck or otherwise is subject to malfunction.

The operation of the apparatus will now be described with particular reference to FIGURES 4, 5, 6 and 7. For the purposes of describing the operation, only the left side parts of the apparatus will be referred to, it being understood that those on the right side will operate similarly. As can be seen in FIGURE 4, the boom 21017 is sloped forwardly slightly from the vertical position. The drum 240 is positioned vertically. Under these conditions the cylinders 220, pin 224 and pivot 262 support substantially the entire weight of the lifting assembly 232. Accordingly, the connecting rod 220a acts as a tension element.

In the first stage of operation, the cylinder 220 is operated appropriately to extend rod 220a as shown in FIG- URE 5. (In this figure the boom 21011 has been raised slightly.) The rod 220a continues to act as a tension element. It should be noticed that through the initial extension of the rod 220a, all of the connecting elements exemplified by the link 228a are pivoted in a clockwise direction relative to the lifting assembly 232. As can be seen in FIGURE 5, the rotation of link 228a and the other similar links brings the extension E into proximity with the fixed stop 264. The fixed stops limit the movement of the connecting links about the pivots 262 in the direction of the actuator 210. It should also be noticed that gravity has caused the movable stops exemplified by stop 270a and 27% to swing in a clockwise direction relative to the lifting assembly 232 under the influence of gravity. With the lifting assembly in the position of FIGURE 5, the edge 276 of the movable stops has been elevated slightly above the lower end of the extension E of each connecting link.

It can be readily seen that by extending the connecting rod 220a of the cylinder 220 slightly further than the position of FIGURE 5, the extensions E will contact the lower surface of each fixed stop 264 positioned adjacent to it. When this takes place, the connecting links will become rigidly associated with the lifting assembly and will move as a single unit with the lifting assembly. The pivots 224 and 226 will then begin to swing away from the booms 2101; and 212b and the load (drum 240) will be partially shifted to fixed stops 264. A portion of the load will remain supported by the fixed stops 264 until drum 240 reaches its lowermost or neutral position as shown in FIGURE 6.

Continued extension of the connecting rods will cause the extensions E at the lower ends of the connecting links to move toward the right as seen in the figures away from the fixed stops 264. By this time, however, the action of gravity has caused the movable stops, all of which are exemplified by the stops 270a and 27012 in FIGURE 6, to move to a position so that the edge 276 is immediately adjacent the side edge of the extension E. Since the stops 270a and 27012 are in alignment with the connecting links continued extension of the connecting rods 220a and 222a as seen in the figures will cause the engagement of the links and the movable stops as seen in FIGURE 7 so that during the last period of extension of the rods, a portion of the load 240 is supported by the movable stops 270. The cylinders and connecting rods then act as pressure exerting elements. When the cylinders 220' and 222 are operated in a reverse direction, the series of events described above will occur in reverse order.

It can be seen by comparison of FIGURES 4 and 7 that the lifting assembly 232 has been moved through an arc of about 180 relative to the boom members 210 and 212 and that the drum 240 in the position shown in FIG- URE 7 is inverted sufficiently so that there will be very little opportunity for material to remain trapped within the drum. It should also be noticed that this has been accomplished although the pivot 224 connecting the links and the actuator has moved through a much smaller arc (about 130). It should be noted too that little problem is presented by the interference of one part with the proper operation of another. Accordingly, the design is suited for application on a wide variety of machinery. Moreover, the pivot 262 between connecting links and the lifting assembly 232 is capable of moving downwardly beyond the axis of the boom members 210 and 212 (to an overcenter position) without the free end of the actuator connecting rods having moved through a similar arc. While the invention has a high degree of utility without the movable stops being used in any application where the load must be elevated beyond its lowermost position or neutral position shown in FIGURE 6, movable stops are beneficial. Since the movable stops are operated by gravity, their operation is self-contained. Accordingly, the invention is more universally applicable to a variety of equipment and no special control is necessary for placing it in the engaged position.

A great many variations and modifications will be apparent to those skilled in the art once the principles of the invention are understood. The invention is limited only in the terms of the appended claims.

I claim:

1. The combination comprising a tilting mechanism, a lifting assembly, an implement having an actuator, a pivotal connection between the implement and the lifting assembly, a connecting link movably mounted upon the lifting assembly for joining the actuator and the lifting assembly, a fixed stop means for limiting the movement of the end of the connecting link joined to the actuator relative to the lifting assembly in the direction of the actuator whereby the lifting assembly will be controlled in its pivotal movement by the link alone during the first portion of the extension of the actuator and continued extension of the actuator will cause the controlling force to be applied by the link through the fixed stop means.

2. The apparatus of claim 1 wherein a means is provided for limiting the motion of the connecting link any substantial distance away from the fixed stop when the actuator is extended sufficiently to tilt the lifting assembly beyond its lowest point.

3. A tilting mechanism for a lifting implement having a boom, an extensible actuator and a load-lifting assembly pivotally secured to the end of the boom for tilting the lifting assembly about a horizontally disposed transverse axis, said tilting mechanism comprising a link means connected to said lifting assembly and having an upper end portion connected to the actuator, a fixed stop on the lifting assembly positioned to engage the link and located to prevent pivotal movement of the link toward the actuator beyond a predetermined position relative to the lifting assembly whereby tension exerted by the actuator will be applied to the lifting assembly through the fixed stop during a portion of the stroke of the actuator and a movable stop positioned to limit the pivotal movement of the link on the lifting assembly in the direction opposite the fixed stop only when the actuator is extended sufliciently to move the lifting assembly beyond its lowermost position relative to the boom.

4. The apparatus according to claim 3 wherein the movable stop'comprises a member pivotally connected to the lifting assembly having a weighted portion and a linkengaging portion, the pivotal support for the movable stop being properly positioned to locate the link-engaging portion thereof adjacent the link when the lifting assembly has been moved to a downwardly depending position on the boom.

5. The apparatus of claim 1 wherein a plurality of said connecting elements are provided and such elements are positioned on opposite sides of the lifting assembly in parallel relationship with each other and supported for pivotal movement about a horizontally disposed transverse axis.

6. The apparatus of claim 1 wherein the lifting assembly comprises a power-operated clamp mechanism.

7. The apparatus of claim 1 wherein the lifting assembly comprises a scoop shovel.

8. The apparatus of claim 1 wherein said actuator comprises a hydraulic cylinder.

9. The apparatus of claim 1 wherein the lifting assembly includes at least one vertically disposed longitudinally extending plate on each side thereof and the fixed stop comprises an element rigidly secured to said plate and positioned forwardly of said link.

10. The apparatus of claim 3 wherein a plurality of said movable stops are provided, each of said stops being independently movable whereby the malfunction of one of the movable stops will not interfere with the proper movement of other movable stops to the link-engaging position.

7 8 11. The apparatus according to claim 3 wherein a sup- FOREIGN PATENTS port member is secured to the lifting assembly in a position to limit the pivotal movement of the movable stop 1,330,859 3/ 1962 Franceaway from the link means.

5 GERALD M. FORLENZA, Primary Examiner.

References Cited UNITED STATES PATENTS 2,959,444 11/1960 Callender 294-88 X US. Cl. X.R. 3,107,114 10/1963 Knoell 294 73 3,138,275 6/1964 Dempster 29473X 10 106 GEORGE F. ABRAHAM, Assistant Examiner. 

